Re: No go in drive.

[fisherman6]

quote PugetSoundBoater:

quote Fisherman6:

How did you measure spark? open air tester set to 1/4″? Spark plugs held against the block and pulled the rope? Are the plugs new? I have had spark plugs fire in open air but not in the cylinder in a compressed fuel-air mixture on more than one occasion.
-Ben

On a side note- seems real strange that a spark plug would not fire under compression. Might it be a semi faulty plug? I don’t mean to jack this thread.

Either a faulty plug or a fouled plug. Either way I have seen them make a spark in open air, but not make a spark in the cylinder when cranking / running. The resistance is a lot higher across the plug gap in the compressed fuel-air mix. This is why you can see a spark in open air but it sometimes still will not fire in the engine. I use the inline neon spark testers to check them and track down ignition issues to a certain cylinder most often. I have also used a timing light to test them. If the plug doesn’t fire, the inductive pickup won’t fire the Xenon flash. Sometimes the neon testers will still get a dimmer light, but will be considerably brighter on the plug(s) that fire if you use multiple testers at once. I find them handy to track these issues down.
-Ben

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